An antenna device is sometimes mounted in an electronic apparatus, such as a smartphone or tablet terminal, in order to perform contiguous communication such as Near Field Communication (NFC). In the case of mounting an antenna device in an electronic apparatus, the antenna device is required to be compact, to be able to connect reliably to the mainboard of an electronic apparatus, and to be easy to mount in the electronic apparatus.
In general, an antenna device includes an antenna substrate onto which are mounted an antenna coil for transmitting and receiving signals, a connection terminal for connecting electrically to the mainboard of the electronic apparatus in which the antenna device is mounted, and an electronic component such as a resonant circuit, a matching circuit, a filter, and a Radio Frequency Integrated Circuit (RFIC). The size of the antenna coil is determined by the communication characteristics that are required. On the other hand, the connection terminal and the electronic component do not relate directly to the transmission and reception of signals and are thus a factor inhibiting a reduction in size of the antenna device.
Therefore, JP 5545371 B2 (PTL 1) discloses an antenna device including a first base member on which an antenna conductor is disposed, a second base member on which an electronic component is disposed, and a flexible substrate (antenna substrate) including a bent portion that connects the first base member and the second base member, wherein the flexible substrate is bent at the bent portion so that the main surface of the first base member and the main surface of the second base member face each other. According to this antenna device, the antenna substrate is bent at the bent portion. Therefore, in plan view, the area when mounting the antenna device can be reduced.